1. Field
The subject device is in the field of apparatus for propelling vessels, particularly hand operated apparatus such as oars, hand driven paddles, paddle wheels, propellers and the like. More specifically it is in the field of apparatus for assisting in the propulsion of apparatus known as water walkers, water walkers comprising flotation apparatus on which the user stands to be supported on the surface of a body of water and to be propelled across the surface by a walking motion.
2. Prior Art
Prior art apparatus useful in assisting in the propulsion of water walkers and the person(s) using them are shown in the following U.S. Pat. Nos. 3,027,576, 3,800,734, 4,527,984, 4,587,038, 4,650,433.
As indicated by the disclosures made in these patents the propulsion assistance apparatus is hand held and operated, comprising a shaft or the like having a handle at one end and a propulsion device at the other. The propulsion devices are intended to engage the water when forced aft by the user to provide a forward thrust to propel the user and to have minimal resistance to the water when moved forward by the user in preparation for making another propulsion thrust in the aft direction. A classic example of this type of apparatus found in nature is the feet of aquatic birds which fold closed on forward motion and open broadly for the thrust stroke.
Some of the prior art devices of the subject type are designed to have the water engagement apparatus always in the water during use with the apparatus changing configuration to provide maximum resistance to motion in the water during the thrust stroke and minimum resistance during the return stroke. Other prior art devices are designed to be in the water during the thrust stroke and out of it during the return stroke. In others the propulsion apparatus is only partly removed from the water during the return stroke and the subject apparatus is of this type since development work indicates that, with certain conditions met, this type is the most effective of the three in terms of propulsion achieved relative to skill and effort required. The conditions include automatic operation at desired immersion levels during thrust and return strokes, rapid expulsion of air from the propulsion apparatus at the beginning of the thrust stroke and no manual adjustments required for operation.
Accordingly, the objectives of the subject invention are to provide water walker's propulsion poles that meet the three cited conditions and are durable, lightweight and easily manufactured.